Google: alt text is extremely helpful for Google Images

On Twitter, Google’s John Mueller said that the image alt text is extremely helpful for Google Images. If you want to get ranked in Google images, you should make sure that your images have a descriptive image alt attribute:

Alt text is extremely helpful for Google Images — if you want your images to rank there. Even if you use lazy-loading, you know which image will be loaded, so get that information in there as early as possible & test what it renders as.